1. Field of the Invention
The present invention relates to a double-sided cutting insert.
2. Description of the Related Art
Generally, a cutting tool is used for cutting irons, non-iron metals, or non-metallic materials, and is mounted on a machine tool to process a workpiece into a desired shape. Such machine tool includes a cutting insert having a cutting edge, and a tool holder to secure the cutting insert in place.
By way of example, a milling cutter uses the cutting insert in which length of the cutting edge contributing to cutting has to increase to enable deeper cuts in the orthogonal or lateral cutting. This leads into increased resistance on the overall cutting edge. Accordingly, various researches have been conducted to improve machinability and lifespan of the machine for high speed cutting, high feed cutting, or high depth cutting.
FIG. 9 illustrates an example of a conventional double-sided cutting insert disclosed in WO 97/17157. For reference, FIG. 9 corresponds to FIG. 3 of WO 97/17157 in which the reference numerals of WO 97/17157 are used for convenience of illustration. Accordingly, reference numeral 30 denotes a cutting edge and reference numeral 21 denotes a major lateral surface.
Such conventional double-sided cutting insert is formed in negative configuration in which the major lateral surface is formed in negative type to design the cutting insert into two faces so that top and bottom surfaces can be used by turns. Since the surface of the workpiece and the cutting edge forms negative rake angle therebetween in the conventional double-sided cutting insert, machinability of the cutting insert deteriorates.